➤ Problem Link : 1284C. New Year and Permutation
✅ C++ Solution :
#include<bits/stdc++.h>
using namespace std;
#define ll long long int
ll fact[250001];
int main()
{
ll n,m;
cin>>n>>m;
fact[0]=1;
fact[1]=1;
for(ll i=2;i<=n;i++)
fact[i]=(i*fact[i-1])%m;
ll ans=0;
for(ll i=1;i<=n;i++)
{
ll curr=(n-i+1)%m;
curr=(curr*(n-i+1))%m;
curr=(curr*fact[i])%m;
curr=(curr*fact[n-i])%m;
ans=(ans+curr)%m;
}
cout<<ans;
}
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I am a Member Technical at D.E. Shaw India Pvt. Ltd. CodingWithArt is a blog where you find tricks and solutions to challenging coding and development problems. I aim to build a universal tech platform for every enthusiast out there.